p-DIALKYLAMINOSTYRYL DYES DERIVED FROM 5-ARYLAMINOTHIADIAZOLES

By condensation of the following pairs : (I) 5-phenylamino-2-methylthiadiazole and p-dimethylarninobenzaldehyde, (2) 5-phenylamino-2-methylthiadiizole and p-dimethylaminobenzaldehyde methiodide, (3) 5-pbanylamino-2:3-dime­thylamindia soliurn iodide and p-dimethylaminobenzaldehyde, three compounds (one colorless, one yellow and the third, red) have been obtained and their colours explained in terms of resonance theory. Six 5-arylamino-2:3-dimethyl-1:3:4- thiadiazoliurn iodides have also been prepared and condensed with p-dimethylaminobenzaldehyde and p-diethylamino­benzaldehyde to yield the corresponding p-dialkylaminostyryl dyes. Their absorption spectra have been measured and their deviations calculated and compared with the deviations obtained in case of p-dialkylaminostyryl dyes derived from quinoline, benzothiazole and thiazoles. Since deviations are a measure of basicity, the greater deviation of dyes derived From thiadiazoles indicates that it is mare basic than benzothiazole or quinoline. The sensitisation spectra of dialkylamino­styryl dyes have also been measured